Belt buckles for seat belt devices of motor vehicles generally function to lock securely to the vehicle a belt tongue (or “latch plate”) that is held and slides along a belt strap (or “webbing”) or is firmly connected to one end of a belt strap. For this purpose, the seat belt buckle includes an insertion slot for the belt tongue and a locking mechanism that can be released via a push button. The locking mechanism is spring-loaded and locks the belt tongue automatically when it is pushed into the insertion slot. To release the belt tongue, the occupant presses down on the push button, releasing the locking mechanism and ejecting the tongue by a force produced by the spring in the locking mechanism.
Such seat belt buckles have long been prior art. A problem with such belt buckles is that to fasten it, the occupant must locate the relatively narrow insertion slot of the buckle, into which he or she inserts the belt tongue to fasten the seat belt.
From DE 39 04 125 (A1) it is known to provide a light source on the buckle that is coupled to predetermined light-emitting surfaces of the buckle via a light-conducting material. Here the light-emitting surfaces are the push button itself and an emitting surface disposed on a lateral surface of the insertion slot opposite the push button. Since the push button must be embodied movable in order to function, the light-conducting material fixedly disposed in the push button must be positioned in the push button such that the surface where the light enters the fiber-optic material when the push button is in the non-depressed position will be connected by lighting technology to the external light source. If, in this position, the light entry surface of the fiber-optic material is not connected to the external light source by lighting technology because of production-related shape deviations or mechanical influences, the light will not, or will incompletely, be guided into the push button, causing the push button itself not to illuminate or to illuminate more weakly than desired.
From DE 10 2007 047 704 (A1), it is also known to provide the seat belt buckle with a light guide that includes at least two light-emitting surfaces disposed at the ends of the insertion slot. The light-emitting surfaces themselves are formed triangular and are disposed in a free triangular surface of the front side of the housing between the edge of the housing and a conical lateral surface of the push button. This way the light-emitting surfaces in particular are dimensioned so that they fill the free surfaces as fully as possible at the corners of the front side of the housing so as to achieve the greatest possible luminosity.
The object of the present invention is to provide an illuminated seat belt buckle of the above-described type that will make it very easy to locate the buckle and the push button for the fastening and unfastening actions.
To achieve this object, an illuminated belt buckle having the features described herein is proposed. Additional preferred embodiments of the invention can be found in the Figures, and the associated descriptions.
According to a feature of the present invention, it is proposed that the light-emitting surface on the seat belt buckle has a linear contour, with its shape matching the shape of an edge side of the push button disposed laterally in the direction of the insertion slot.
The advantage of the proposed solution is the fact that locating the buckle and especially the push button is simplified, first, by the very fact of illumination. Second, the position of the push button is further characterized by the shaping of the light-emitting surface, so that locating and operating the push button are simplified. In this way the occupant is able to locate the push button simply by the position of the luminous light-emitting surface alone, after operating it several times and achieving a certain level of practice, and in knowing the position of the light-emitting surface at the edge of the push button. In the simplest case, after a certain amount of practice, the occupant can release the buckle by pressing “blindly” on the surface next to the light-emitting surface without having to recognize the push-button itself. In this case, operating the push button is made easier by the fact that the seat belt buckle, both in the normal fastened position and in the unloaded or unfastened position, has a basic orientation in which the push button is always positioned on the same side of the light-emitting surface. Since the insertion slot in turn is always disposed in a fixed orientation with respect to the push button, this also lets the slot be located easily in order to fasten the seat belt.